Me. Rev. Stat. tit. 3, § 4

A postaudit of all accounts and other financial records of the Legislature, the Governor's office, except the Governor's Expense Account, and any agency or office in the Executive Department which has not been audited by a state or federal agency within the preceding 24 months, shall be performed at least once every 2 years by independent certified public accountants designated by the Governor. Such audit report shall be filed with the Legislature and with the State Library.